Generally, exhaust gases released from various types of industrial facilities include fine particles. To remove particulate contaminants from exhaust gases, devices such as a cyclone and a bag filter dust collector are used. When exhaust gases pass through the cyclone, larger and heavier dust is captured, and un-captured smaller and lighter dust is collected by the bag filter dust collector. The bag filter dust collector is designed to separate solids from gases through a filter, and generally the bag filter can filter out dust down to 0.1 μm in size.
FIG. 1 shows a conventional bag filter dust collector, called a bag housing, including a bag filter and a blower, and the conventional art is described below with reference to the drawing.
In FIG. 1, (a) is a top view and (b) is a side view. Dust laden air entering through an inlet 1 beneath passes through a bag filter 3 at an upper part, so that dust is trapped on the surface of the bag filter 3, and purified air is discharged through an outlet 2 on the top via the bag filter 3.
The bag filter dust collector has high dust collection efficiency, but in the course of filtering, dust layers trapped in a filter cloth become thicker and a pressure loss increases, so it is necessary to blow dust on the surface of the bag filter by periodic cleaning operation. The cleaning operation mainly employs a cleaning apparatus using compressed air including a compression air tank 8, a blow pipe 6 and nozzles 7, and is performed by blasting compressed air having strong energy into the bag filter through the nozzles 7 to blow off dust attached to the surface of the bag filter 3, and consequentially reduce a pressure loss. In this instance, if cleaning is inadequate, compressed air blasted for cleaning is adjusted such that the pressure of compressed air is higher or the blasting cycle of compressed air is shorter.
The cleaning operation is performed at a predetermined time interval to cause dust on the surface of the bag filter to fall down and be gathered in a dust reservoir 5 through a dust discharge device 4, and eventually, to be forced outwards. However, while dust is falling, some may be attached to the inner wall, and if dust build-up on the inner wall continues and is not properly removed, an outlet may be clogged in the end. To solve the problem, an air knocker or a vibrator is generally used, and in this case, there is a dedusting effect at certain areas, but adjacent facility is damaged by vibration.